Reclosing circuit breaker



July 7, 1936. P. B. PARKS 'RECLOSING CIRCUIT BREAKER Filed Oct. 12, 19340M.- Unrmgus iii Gil

Patented July 7, 1936 UNITED STATES PATENT OFFICE RECLO SING CIRCUITBREAKER Application October 12, 1934, Serial No. 748,096

4 Claims. (01. 175-4594) r This invention relates to certain new anduseful improvements in reclosing circuit-breakers, and also to animproved safety circuit controlled by this circuit breaker so as toprevent the too prolonged flow of a destructive current through thecircuit and thus protect electrically actuated devices in this circuit.

As is well known, the flow of an abnormal current in an electriccircuit, caused by an overload or a short circuit may cause damage tothe electrical apparatus in the circuit. Also some electrical devicesare adapted to be actuated by a rather heavy current which flows onlymomentarily and is then cut off. If this current were allowed to flowfor too long a time the apparatus would be injured. To prevent this,fuses or automatic circuit-breakers are often provided in the circuit. Afuse will burn out and must be replaced before the circuit can bereestablished. Many circuit breakers are of the type which must bemanually reset before the circuit can be reestablished. According to thepresent invention, the improved circuit-breaker is of the type which isautomatically re-closed at intervals, so that if the abnormal conditionis only temporary the circuit will be automatically reestablished. Anapparatus of this general type is disclosed and claimed in the patent toParks et al. #1,922,452, granted August 15, 1933. The present inventionrelates to improvements in an apparatus of this type, as hereinafter setforth. Also, according to the present invention, the main operatingcircuit is not entirely broken, but a high-resistance signal device isthrown intothe circuit when the circuit-breaker is open. Thishigh-resistance device functions to cut down the current flow to such anextent that the apparatus will not be injured, and at the same timegives a visible or audible signal so that the attendant will becomeaware of the abnormal condition and take steps to correct the same.

Briefly described, the controlling mechanism comprises a self-closing,normally closed circuitbreaker in the main circuit, and anelectromagnetic device which will open the circuit breaker whenenergized. A heating element included in the main circuit is positionedadjacent a thermostatic device within a closed heating chamber. Theprolonged passage of a heavy current through this heating element willaffect the thermostatic device so as to close a switch which completes acircuit through the electromagnetic device thus opening the circuitbreaker. The closing of the switch also completes an energizing circuitfor an electromagnet which tends to hold the'switch closed so as todelay the re-closing of the main circuit for a more or lesspredetermined length of time.

The principal object of this invention is to provide an improvedoverload safety circuit of the type briefiy described hereinabove anddisclosed more in detail in the specifications which follow.

Another object is to provide an improved reclosing circuit-breakerincluding electromagnetic means for opening the circuit and delaying there-closing of the circuit.

Another object is to provide an improved means for automaticallythrowing a high-resistance signal device into a circuit so as to reducethe current flow and give an indication of the abnormal operatingconditions.

Other objects and advantages of this invention will be more apparentfrom the following detailed description of one approved form ofapparatus constructed and operating according to the principles of thisinvention.

The accompanying drawing is a diagrammatic illustration of the improvedcircuits and the improved safety mechanisms included therein.

The combination shown includes generally a source of electric power A(here shown by way of example as a battery), a pair of electricallyoperated valves B and B, a pair of relays C and C for controlling theactuating circuit for the valves B and B respectively, a pair oftemperature responsive mechanisms D and D respectively controlling therelays C and C, the re-closing circuit breaker E, the assembly F forcontrolling the circuit-breaker, and the signal device G.

The valves B and B are similar and of the type commonly in use forcontrolling the flow of steam through the radiators of a railway carheating system. Each valve is controlled by a handle l, pivotedintermediately at 2, the valve being shown in the closed position. Whenhandle l is swung to an oppositely inclined position at the other sideof the vertical, the valve will be open. A pair of electric motormechanisms 3 and i are provided for respectively moving the valves toopen and closed position. As here shown these motors are in the form ofsolenoids 3 and 6 having their respective cores 5 and ii carried at theends of an operating rod l having an intermediate yoke 8 which engagesone arm of the handle or lever i. When solenoid 4 is energized, thehandle will be swung to the position. shown in the drawing and the valvewill be closed. When solenoid 3 is energized, the handle will be swungto an oppositely inclined position and the valve will be open. Asnap-switch 9,

actuated by a yoke it on theopposite end of lever l, comprises a movablecontact [ll adapted to engage alternatively with the fixed contacts i2and I3. The purpose of this snap-switch is to break the operatingcircuit of solenoid 3 or 4 as soon as the valve movement has been com.-pleted. A rather heavy current is used in the motor, and if the flow ofthis current was allowed to persist for too long a time damage might bedone to the electrical mechanism. This flow of current will normally beout ofi by the snap-switch 9 as soon as one of the valve movements hasbeen completed, but in case the valve should stick or some otherabnormal condition should arise, the snap-switch 9 might fail to breakthe circuit at this point and the continued flow of current might proveto be destructive. To prevent this, the safety mechanisms E, F and G,hereinafter described, are provided.

The relay C is normally energized through the following closed circuit:from positive main 04 through wires i5 and i6, resistance ill, relaycoil i8, wire l 9, resistance 23, and wire M to the negative main 22.When so energized, the movable contact plate 23 will be pulled down intoengagement with the pair of fixed contacts 24 and 25. The thermostaticmechanism D is adapted to short circuit this current around the coil itso as to deenergize the relay and permit the spring 26 to move thecontact plate 23 into engagement with the pair of fixed contacts 27 and28 (as shown in the drawing).

This thermostatic mechanism D is of a well known type comprising aplurality of mercury tube thermostats 29, 30 and 3!] adapted to functionrespectively at certain predetermined high, mediumv and lowtemperatures, the thermostat in control of the relay at any given timebeing determined by the positioning of the manually operatedselectorlswitch 32. This switch comprises a movable contact arm 33,always in engagement at its lower end with the arcuate contact plate 34,and adapted to be moved selectively into engagement at its upper endwith any one of the fixed contacts 35, 36 or 371. As shown in thedrawing, the low temperature thermostat 30 is in control of the relay.When the mercury column 38 of this thermostat rises sufficiently tuengage the fixed contact 33, a shunt circuit around the relay coil 118will be completed as follows: from one terminal of this relay coilthrough wire 40, thermostat 3|, wire 4|, fixed contact 3], movablecontact arm 33, fixed contact 34, and wire 43 to the other terminal ofcoil W. This will deenergize the relay and permit spring 26 to move thecontact plate 23 to the position shown in the drawing. When thetemperature in the space whose temperature is to be controlled by themechanism D falls below the predetermined temperature for whichthermostat 3| is adjusted, the mercury column will break this circuit bymoving down out of contact with the fixed contact member 39 so that thisshunt circuit will be broken and the relay coil l8 will again beenergized so as to draw the contact plate 23 down into engagement withthe lower contacts 24 and 25. When the movable selector arm 33 is movedinto a vertical position in engagement with the fixed contact 36, anexactly similar control circuit will be completed through the mediumtemperature thermostat 40, but at a somewhat higher temperature. Whencontact arm 33 is moved into engagement with the contact 35, the controlcircuit will be completed at a still higher temperature through Wire 40,thermostat 23, and wires 44 and 43 directly back to the relay coil.

The circuit-breaker E comprises the movable contact plate'45 which isnormally held by spring 46 so as to bridge the two fixed contacts 4'!and 48. When the electromagnetic device 49 is energized, the movablecontact plate 45 will be drawn down into engagement with the stops 59 soas to break the circuit between contacts 4'! and 48. The controlmechanism F, which will be hereinafter described more in detail,includes a heating element 5! (usually a resistance coil) which willbecome rather highly heated when the normal operating current for thevalves B or B flows therethrough for any unusual length of time.

Returning now to the operation of the valve mechanisms, the valve B isshown in the drawing as closed, the temperature in the space to beheated having risen to or above the predetermined temperature for whichthermostat 3| is adjusted. When the temperature in this space fallsbelow the predetermined. temperature, the shunt circuit throughthermostat 3| will be broken and relay 0 will again be energized so asto pull down the contact plate 23, whereupon an operating circuit foropening the valve 3' will be completed as follows: from positive main Mv through wires l5 and 52, relay contacts 24, 23

and 25, wire 53, solenoid 3, wire 54, snap-switch contacts l2 and H,wires 55, 56 and 57, circuitbreaker contacts 43, 45 and 47, wire 58,heating element 5| and wire 59 to the negative main 22. Solenoid 3 willnow draw in the core 5 and move the valve to open position, and at thecompletion of this movement the actuating circuit will be broken bysnap-switch 9 moving the contact it over into engagement with the otherfixed contact l3. When the temperature again rises to the predeterminedpoint, the shunt y'circuit through thermostat 3| will again be completedso as to deenergize the relay C, whereupon relay contact plate 23 willagain be moved up into engagement with fixed contacts 27 and 28 thuscompleting an actuating circuit for valve motor 4 as follows: frompositive main l4 through wires l5 and 60', relay contacts 27, 23 and 28,wire 6|, solenoid 4, wire 62, snap-switch contacts l3 and H, and thenceas before through wires 55, 56 and 51 to and through the circuit-breakerE and heating element 5|. As soon as the valve has been moved to closedposition, this circuit will be broken by snap-switch 9 moving contact llback into engagement with contact l2, all as shown in the drawing.

The valve mechanism 13' may be controlled in an exactly similar mannerthrough relay C by means of the single thermostat D. It will be notedthat all of these valve-actuating circuits pass through thecircuit-breaker E and the heating element 5|. It will also be understoodthat the valve operating assemblies B and B, as well as their controlmechanisms C and C and D and D are shown and described principally forthe purpose of illustrating a type of electricallyoperated apparatusthat may be protected by the improved safety mechanisms E, F and G.

The control assembly F comprises the casing 63 provided with closure 64so as to completely A suitable thermostatic element is also iii heatingelement 5|, so as to respond quickly to temperature changes produced bythe prolonged flow of current through the coil 5|. Preferably thisthermost tic ele ent is in the form of a bimetallic bar 6 ored at oneend 69 in the casing and in electrical connection with binding post 61.A movable contact 10 carried by the free end of bar 68 is adapted toengage with fixed contact II mounted in the casing wall so as to form anormally open switch. When the bar 68 is heated, it will warp downwardlyso as to bring switch contact I into engagement with the fixed contact'H. The armature 12 of an electromagnet 13 is mounted in the lower wallof casing 63 so as to be in position to attract and hold the bar 68 inits warped position when the electromagnet is energized. This magnet isnot of sufiicient strength to permanently hold the thermostatic bar inthis warped position, but it will resist the tendency of the bar tostraighten out so that the thermostatic bar must cool considerablybefore it can move away from the magnet and break the switch contacts.

The signal device G is in the form of an electric lamp, or other visibleor audible signal device of rather high resistance, connected throughwires 14 and 15 in a branch of the main circuit in parallel with orshunted around the circuit closure contacts 47 and 48.

Assuming now that one of the valve mechanisms B or B should stick, orsome other abnormal condition should arise so as to cause one of theheavy operating currents to persist for an abnormal length of time, theheating element will become heated sumciently to cause the thermostaticbar 68 to warp downwardly and close the switch contacts and H so that anenergizing circuit for electromagnet 49 will be completed as follows:From positive main l4 through wire 14, electromagnetic device 49, wireI5, switch contacts H and Ill, thermostatic bar 68, binding post 61, andwire 59 to the negative main. This will energize the electromagneticdevice 49 and draw down the contact plate 45 so as to break the mainoperating circuit between contacts 41 and 48. This main circuit will notbe entirely broken but will now be shunted through the high resistancesignal device G. This device G will now be illuminated or will giveother indication to the attendant that some abnormal condition exists,and at the same time it will so cut down the current flowing in thismain circuit that it will no longer be injurious to the valve-operatingmechanism, nor will it be suiiiciently strong to highly heat the element5| which will now begin to cool on. At the same time an energizingcircuit for the holding magnet 13 will be completed as follows: Frompositive main l4 through wires 14 and 16, magnet 13, wire I3, switchcontacts H and Ill, thermostatic bar 68, binding post 61, and wire 59 tothe negative main. This magnet will tend to hold the switch in closedposition, and will prevent chattering of the switch. As soon as thethermostatic bar 68 begins to cool off it will tend to straighten outand break the energizing circuit through the switch, but the magnet 13will tend to hold the switch in closed position for a certain timebefore the thermostatic bar develops enough energy to break the switchcontacts. Also the housing of the heating element 5| and thermostat 68within the closedcasing tends to delay the loss of heat from theseelements and thus delay the re-closing of the circuitbreaker and themain operating circuit, and cause the signal D to operate for a suitablelength of time. After a certain time, the thermostat 68 will cool offsufficiently to overcome the attraction of magnet 13 and break theswitch contact thereby deenergizing the electromagnets l3 and 49,

and the circuit-breaker will again be closed by v spring 46 thusshort-circuiting the signal G and again completing the normal operatingsystem. If by this time the abnormal condition in this operating circuithas ceased to exist or has been corrected, the devices E, F and G willremain in this normal position (as shown in the drawing), but if themain circuit is still closed the element 5| wil again heat up so as tocause another movement of the thermostatic bar and the operationspreviously described will be repeated so as to again open thecircuit-breaker and cause the signal G to operate. This cycle of eventswill be continued indefinitely until the main operating circuit isbroken at some other location, by the proper operation of the snapswitches 9, or some equivalent operation in case other types ofmechanism are positioned in this circuit.

By inclosing the heating element 5| and thermostat 68 in closejuxtaposition within the airtight casing 63, the heating element and barwill heat up quickly when subjected to an abnormal current flow, andalso the slow dissipation of heat from this heating chamber 65 will helpto delay mally closed circuit-breaker in this circuit, and anelectromagnetic device adapted to open the circuit-breaker and therebybreak the main circuit, a thermostatic-switch assembly comprising anelectric-heating element, a thermostatic element positioned in closeproximity to the heating element, a casing intimately enclosing theheating and thermostatic elements to form a closed heating chamber aboutthese elements so as to expedite the transfer of heat therebetween andminimize the heat losses from the thermostat, a switch mounted in thecasing and adapted to be closed by the thermostat when heated, electricterminals for the heating element and switch carried by the casing, theheating element being connected in the main circuit, an electro-magneticdevice mounted on the casing and having an armature projecting through awall of the casing into position to attract'the thermostatic element andhold the switch closed while the thermostat is heated, and energizingcircuits for the two electromagnetic devices, both of'said circuitsincluding the switch and being opened and closed thereby.

2. In combination with a main circuit, a normally closed circuit-breakerin this circuit, and an electromagnetic device adapted to open thecircuit-breaker and thereby break the main circuit, the main circuitincluding a branch shunted around the circuit-breaker, and ahigh-resistance signal device in said branch circuit, athermostatic-switch assembly comprising an electricheating element, athermostatic element positioned in close proximity to the heatingelement, a casing intimately enclosing the heating and thermostaticelements to form a closed heating chamber about these elements so as toexpedite the transfer of heat therebetween and minimize the heat lossesfrom the thermostat, a switch mounted in the casing and adapted to beclosed by the thermostat when heated, electric terminals for the heatingelement and switch carried by the casing, the heating element being lidconnected in the main circuit, an electromagnetic device mounted on thecasing and having an armature projecting through a wall of the easinginto position to attract the thermostatic element and hold the switchclosed while the thermostat is heated, and energizing circuits for thetwo electromagnetic devices, both of said circuits in== cluding theswitch and being opened and closed thereby.

3. In combination with a main circuit, a nor= mally closedcircuit-breaker in this circuit, and. an electromagnetic device adaptedto open the circuit-breaker and thereby break the main circuit, athermostatic-switch asernbly comprising a casing enclosing a shallowheating chamber, a heating element mounted within this chamber, athermostatic bar anchored at one end in a wall of the casing andprojecting into the chamber in proximity to the heating element, amovable switch contact carried by the free end portion of the bar, asecond switch contact mounted in one wall of the casing in position tobe engaged by the movable contact when the bar is heated, and terminalsmounted in the casing and connected respectively with the ends of theheating element, the fixed end of the bar, and the fixed switch contact,the heating element being connected in the main circuit, anelectromagnetic device mounted on the casing and having an armatureprojecting through a wall of the casing into position to attract the.bar and hold the switch closed while the bar is heated, and energizingcircuits for the two elecaocaeoe tromagnetic devices, both of saidcircuits including the switch and being opened and closed thereby.-

4. In combination with a main circuit, a normally closed circuit-breakerin this circuit, and an electromagnetic device adapted to open thecircuit-breaker and thereby break the main circuit, the main circuitincluding a branch shunted around the circuit-breaker, and ahigh-resistance signal device in said branch circuit, athermostatic-switch assembly comprising a casing enclosing a shallowheating chamber, a heating element mounted within this chamber, athermostatic bar anchored at one end in a wall of the casing andprojecting into the chamber in proximity to the heating element, amovable switch contact carried by the free end portion of the bar, asecond switch contact mounted in one wall of the casing in position tobe engaged by the movable contact when the bar is heated, and terminalsmounted in the casing and connected respectively with the ends of theheating element, the fixed end of the bar, and the fixed switch contact,the heating element being connected in the main circuit, anelectromagnetic device mounted on the casing and having an armatureprojecting through a wall of the casing into position to attract the barand hold the switch closed while the bar is heated, and

energizing circuits for the two electromagnetic,

